1. Field of the Invention
This invention relates to a backlight module, more particularly to a light guide plate of a backlight module.
2. Description of the Related Art
Backlight modules have been commonly used in display units of numerous electronic devices, such as mobile phones whose display units are generally used to display communication data or information. As shown in FIGS. 1 and 2, a conventional backlight module includes a light guide plate 1 and a plurality of spaced apart light source elements 11 disposed at one side 10 of the light guide plate 1. The thickness of the light guide plate 1 is tapered from the side 10 to the other side 12, and a reflection layer 14 is attached to one surface 13 of the light guide plate 1. The tapered configuration of the light guide plate 1 is used in an attempt to provide even brightness or avoid attenuation of light when light is reflected from the reflection layer 14. However, such a backlight module encounters a problem in that there are dark regions 121 between two adjacent bright regions 120 which are substantially elliptical and which extend in a direction toward the side 12 from the corresponding light source element 11 and that brightness tends to decrease from the side 10 toward the side 12. In order to provide backlight modules with even brightness, further improvements in backlight modules are desirable.